The Dark Knight Rises star, who also has a role in the film, told US radio station Jam'n 94.5: "Lady Gaga is in a scene of it. And I gotta say, she did a really good job. Like, she's a great actress. And I didn't know that."

The 32-year-old continued: "You know she came in and I was like, 'OK sure, they're having a huge pop star do a scene in the movie, I understand.' But then she came in and like, nailed it!

"She had her character down, and she was like a total pro and did a great job. I was really impressed."

Sin City: A Dame To Kill For is directed by Robert Rodriguez and stars a whole heap of A-Listers including Josh Brolin, Eva Green, Mickey Rourke, Jessica Alba and Bruce Willis.

The Sin City sequel hits cinemas in mid 2014, but before that, Gaga is also set to appear in another Rodriguez flick Machete Kills which will be released at the end of this year.